[NTG-context] Letter module

Hello, Is there any updated documentation for the letter/correspondence module? All I can find is version 2010.08.27 and I can see from this list that things have changed, I just don't know where to find out what. Also, can anyone tell me how to remove the label above the date, how to add a pdf containing my letterheading as the page background, and how to add a horizontal line between the backaddress and the toaddress? For the page background I currently have: \setupletter[ backgroundimage={letterhead} ] but it doesn't seem to do anything. I've tried adding the file extension. Thanks, Mo.